I noticed today that when I turn the A/C on, both radiator hoses become constricted (shrivel up as if something is vacuuming out any air)

After letting the engine cool I opened the radiator cap to let air back in - both hoses expanded back to normal. I then started the car and let the engine get back to normal operating temp. No coolant leaks, hoses are fine, engine runs normally. Turn on the A/C and a few minutes later the hoses are shriveled again. The A/C does blow cold air.

Can anybody tell me what the problem is?

This may be related - I've been trying to locate a sort of intermittent "scratchy" sound coming from one of the front of the engine when it's warm and idling with the A/C off. Can't here it during revs. Using an auto stethoscope I've narrowed it down to the A/C compressor, either it has bearings that are failing or its low on freon. Does this make sense?

 

The problem is the hoses. They get hot and can collapse, causing cooling issues. Ive heard of people putting springs and such in the hose to keep it from collapsing. Im sure you can get reinforced hoses also.

 

While the hoses may be part of the problem there should never be any condition that causes vacuum to build in the cooling system (which is what is collapsing the hoses)- they should alway be under pressure any time the engine is warmed up.

The radiator cap may be either bad or not the right one. It should have a little poppet valve built into it that allows flow into the cooling system to prevent ever building vacuum in there (on a stock setup it allows coolant to be drawn back into the radiator from the overflow tank, typically when the engine cools off). You should never have to manually remove the cap to relieve vacuum in the cooling system.

New radiator cap would be the first thing I'd do.

 

Thanks for the response, but I agree with Damon's post - a hose should not collapse in a pressurized system. Air is escaping when the coolant heats and expands, which affects system pressure, which can cause cooling issues. The fact that the hoses collapse is a sign that they are doing their job.

Its the original radiator cap, so it could be bad like you said. Later today I'll check to see if the coolant level in the expansion tank goes down like its supposed to (Just finished driving it).

 

Swapped the old radiator cap with a brand new one - problem solved. Thanks!

 

thats jusy what i was gonna suggest and some radiator hoses have springs in them mostly the lower hose